Mongolians are already struggling with an economic crisis which has seen the currency, the tugrik, depreciate rapidly, making household goods more expensive.

Weather forecasts for next week are predicting temperatures as low as between minus 40 and minus 50 degrees Celsius (minus 40-58 degrees Fahrenheit) in northern and eastern Mongolia.

Government officials have yet to declare a "dzud", but the current climate is ideal for the natural disaster, said Lamjav Oyunjargal, the director for forecasting at the Information and Research Institute of Meteorology, Hydrology and Environment.

"Officially, conditions are very difficult in Mongolia. Mostly we talk about livestock because it's the main income of herder people in Mongolia, but it's also dangerous for humans," Oyunjargal said.

Dulaamsuren, who works at the National Emergency Management Agency in Bulgan province in remote northern Mongolia, said more than 3,000 local herders did not have enough supplies to last through the winter.

"We have enough hay until February or March, but we really should stock up more," he said, adding that the region was now under 40 centimetres (11 inches) of snow, four times the usual level.

The dzud of 2009-2010, one of the most severe in history, saw a total of 9.7 million livestock deaths. As many as 1.1 million head of livestock died last winter.

Winter began early when Mongolia was hit by a "cold surge" in November, plummeting temperatures to around minus 47 degrees Celsius (minus 52.6 degrees Fahrenheit), she said. By December 11, about 70 percent of the country was under snow.

"Already affected areas will get even more snow and colder temperatures," Oyunjargal said, adding the east and north of the country, an area the size of Egypt, were most vulnerable.

Mongolia is one of the most sparsely populated countries in the world, and the extreme cold and snow storms of a "dzud" are a major issue for herders travelling between far-flung towns.

Amid the worst economic conditions since the global economic crisis, the capital Ulaanbaatar is working with international organisations to get assistance to herders.

The government has stockpiled hay and fodder for distribution, but resources are stretched thin as it negotiates with the International Monetary Fund to refinance debt.

Dzuds have become more frequent as a result of climate change, environmental groups have said, putting Ulaanbaatar under increasing strain in recent years.

The mass migration of out-of-work herders into the Mongolian capital over the last decade has seen the rapid expansion of "ger districts", makeshift neighbourhoods named after Mongolia's traditional yurt dwellings.

The residents are not connected to the city's urban heating system, forcing them to burn coal and other materials, including tyres or household waste, to keep warm, creating massive pollution problems.

According to official data on Friday, the air quality index in the northern Ulaanbaatar district of Bayankhoshuu reached a hazardous 1,854, with concentrations of breathable airborne particles known as PM2.5 at 927 micrograms per cubic metre.

The safe recommended level of PM2.5 is 10 micrograms, according to the World Health Organization.

(The story fixes typo in 8th paragraph)

(Reporting by Terrence Edwards; Editing by David Stanway and Michael Perry)